Industrial Grade Reliability
Low power sensor networks have many attractive attributes and with
appropriate care in selection can out perform traditional wired systems,
but not all wireless systems are equal.

Systems operating on a static frequency channel
are often plagued by interference and co-existence problems and point to
point topologies do not always align well with actual field requirements.

The SensiNet system has grown from years of field
experience and been optimized to deliver world class performance by utilizing the following techniques:

Amplification

Frequency Diversity (Frequency hopping)

Path Diversity (Mesh Network)

Self Healing Protocol

Amplification: SensiNet is based on standard IEEE
802.15.4 radios specifcally designed to coexist with WiFi (IEEE
802.11.X) systems thus reducing a significant source of RF interference.

SensiNet is amplified to provide 30 times (15 dB)
the native transmit power of the IEEE 802.15.4 radio allowing longer
range between hops and more robust point to point communication than
systems utilizing unamplfied radios such as Zigbee.

This additonal power also reduces the effects of
physical interferance such as partitions and equipment in the field
environment.

"Shouting louder", although useful is only part
of the solution and the other attributes of SensiNet are equally
important.

Frequency Diversity: The IEEE 802.15.4 radio employs a Direct Sequence Spread Spectrum (DSSS) technique designed to
minimize the effects of interference by 'spreading" the radio signal
over a 3 MgHz band and many wireless systems based on the Zigbee
protocol rely solely on this technique.

SensiNet utilizes this technique but also
dynamically utilizes all 16 channels avialable in the IEEE 802.15.4
radio in a random hopping pattern. This "frequency diversity" virtually
eliminates the effects of RF interference and destructive reflections
which can render other systems unreliable.

In essence, if the SensiNet systems exeriences a
corrupted transmission it simply switches channels, an operation which
is done continuously and automatically.

SensiNet further enhances this technique with a
blacklisting algorithm (not enabled in the EU) which removes error prone
channels from the hopping pattern until they are determined to be
reliable through periodic "probing".

This is a dramatic difference compared to systems
employing the Zigbee protocol, which only operate on a single, manually
selected channel and are incapable of dynamic channel hopping.

Path Diversity (Mesh Network): SensiNet components automatically and
autonomously form into a multipath mesh network upon power up and each
element determines a primary and secondary path with "parents" based on
a variety of Quality of Service factors.

This allows multiple communication paths to be
immediately available in the event of disruption of any path due to
physical interference or hardware failure.

This attribute also allows the network to be
extended beyond the distance available from a single "hop" greatly
increasing reliability and range of the system.

Network communications are bi directional and
each transmission is error checked (CRC) and acknowledged at each "hop"
further enhancing trasmission integrity.

Self Healing Protocol: SensiNet is not only
"expert" at network formation but constantly monitors the health of the
network and is able to "repair" itself in the event of a major system
fault by initiating a reformation process if links remain unavailable
for an extened period of time.

This process is monitored by the SensiNet
Services Gateway which will notify upstream elements of this status and
flag individual elememets as "off line".